1. Field of the Invention.
The present invention generally relates to tools for replacing cutting bits used in roadway reclaiming equipment. More specifically, this invention relates to a device that separates cutting bits from the cutting bit holders that connect cutting bits to rotating cutting drums on road reclamation equipment.
2. Description of the Prior Art.
Typical roadway surface reclaiming machines disclosed in the prior art include rotary driven cylindrical drums with holders holding fixed one or more cutting bits which scarify and mine the top portion of an asphaltic road surface. While several styles of drums have been employed, at least some styles have included an array of cutting bit holders fixed usually by a peripheral weld to the drum surface. Replaceable cutting bits are received within the cutting bit holders which can be periodically replaced as needed. Examples of prior art cutting bit holders are to be found in my U.S. Pat. No. 5,884,979, as well as in U.S. Pat. Nos. 5,582,468 and 5,098,167. Other examples appear as the prior art cited in these patents.
During the operation of such roadway surface reclaiming machines, the cutting bits are exposed to extreme frictional and impact forces. Although these bits are typically manufactured from hardened materials, wear and damage to the cutting bits is inevitable. As the cutting bits wear, the efficiency of the equipment that relies upon them is reduced, slowing the reclamation process and increasing the burdens imposed upon the cutting bit holders, the cutting drums and the equipment that drives these devices. This leads to delay and increased costs for additional maintenance and labor.
However, typical road surface reclamation devices use a large number of cutting bits, thus, the replacement of the cutting bits is a time consuming process, largely because the manual removal and reinstallation cutting bits is often tedious and slow. Thus, replacement of the bits is expensive both because it requires the extended attention of one or more trained mechanics and because all road reclamation operations must cease during replacement of the cutting bits. When circumstances dictate that cutting bits must be replaced during regularly scheduled reclamation activities, hundreds of labor hours can be lost.
Accordingly, what has been sought has been a tool for removing the cutting bits from their holders in a time effective manner.
However, it is often very difficult to remove cutting bits from cutting bit holders. Cutting bits are firmly affixed when they are installed. In operation, the extreme stress, thermal conditions, and environmental contamination to which these products can be exposed can tightly bind these devices.
Thus, what is needed is an effective tool for separating even tightly bound cutting bits from their holders in a time effective manner.
It might appear that a simple solution to this problem lies in providing a powerful device that can exert exceptional amounts of force upon the cutting bit and bit holder in order to separate these components. However, great care must be exercised in the application of large amounts of force to this equipment because the individual cutting bit holding elements in rotary driven cylindrical cutters are often aligned in a known manner to maximize the mining activity and facilitate removal of mine material from the kerf created by the cutting operation. In certain alignment regimens, cutting bit holding elements on one side of the drum are aligned differently than cutting bit holding elements on the opposite side of the drum. Adherence to these alignment regimens is critical to the overall efficiency of the road reclamation process. Because of this, simply providing a tool that uses substantial amounts of force to separate these components will not meet the design objectives unless this force is properly directed and channeled to prevent damage to the cutting bit holders and the drum.
Accordingly, what is needed is an effective tool for separating even tightly bound cutting bits from their holders in a time effective manner while limiting the risk of damage to the cutting bit holder and the cutting drum.
In situations where substantial amounts of force are required to separate the cutting bit from the cutting bit holder, it is occasionally the case that the cutting bit and cutting bit holder separate rapidly. When this occurs it is possible that the cutting bit will be accelerated and will gain some freedom of motion during the removal process. It is, therefore, necessary that the freedom of motion available to the cutting bit is restricted in order to limit the possibility that the cutting bit will unexpectedly contact the user of the tool, the cutting bit holder or the drum.
Thus what is needed is an effective tool for separating even tightly bound cutting bits from their holders in a time effective manner while limiting the risk of damage to the cutting bit holder and cutting drum during the separation process and further restricting the freedom of motion available to the cutting bit after separations.
In accordance with the present invention a tool is provided for separating a cutting bit from a cutting bit holder used in connection with a rotary a cutting assembly for use in a roadway surface reclaiming machine. As is discussed in more detail in U.S. Pat. No. 5,884,979, cutting bit holders are separable components that link cutting bits to a driven and rotating drum in a roadway reclaiming machine. They are fixed to the surface of the rotating drum and aligned in a predetermined pattern. They serve as a buffer between the cutting surfaces of the cutting bit and the driven surface. In extreme situations, they can separate from the driven surface before forces accumulate that will damage or deform the driven surface. They also permit the user of the equipment to replace the cutting bits as necessary without repeated modification of the driven surface.
The present invention is directed toward assisting the replacement of the cutting bits, more particularly it is directed to providing a means of quickly and effectively changing removing cutting bits from the cutting bit holders. The present invention accomplishes this objective by providing a pulling mechanism that is mechanically assisted. In this invention, a bit puller is provided for engagement with the cutting bit and also attached to a powered retractor to forcibly move the cutting bit. The cutting bit and the retractor are fixed to an outer frame or brace. This outer frame or brace generally circumscribes the bit puller to provide an inner space within which the bit puller can be moved by the retractor.
The outer frame or brace also serves to fix the position of the retractor relative to the cutting bit holder when the retractor moves the cutting bit away from the cutting bit holder. To do this, the outer frame or brace has one end that is formed to engage the cutting bit holder and another end fixed to the retractor. As noted above, it may be necessary for the retractor to apply significant force to separate the cutting bit and the cutting bit holder. Accordingly, the engagement end of the outer frame or brace is further defined to confront the cutting bit holder in a manner that limits the possibility that the cutting bit holder will be damaged by the forces created during separation.
To permit the rapid engagement of the connector to the cutting bit, the outer shield is sectioned to permit the user of the tool to laterally introduce the cutting bit into the inner space within the outer shield. This sectioning also permits the user of the tool to quickly engage the bracing surfaces of the outer shield against the appropriate surfaces of the cutting bit holding element. Similarly, the connector is configured with an opening to permit lateral engagement with the cutting bit. In this way, the user of the tool can quickly and effectively engage the connector with the cutting bit and the outer shield with the cutting bit holding element.
Because repair and maintenance circumstances will vary, the relative position of the puller bit and the engagement end of the outer frame or brace must be able to vary to ensure that the connector can engage the cutting bit while the engagement end of the outer frame or brace engages the cutting bit holding element. To accomplish this, one embodiment of the present invention provides a retractor that allows the user to selectively position the connector relative to the engagement end of the outer frame or brace. It can also be readily appreciated that the same result can be accomplished by providing an outer frame or brace that is adjustable.
In another preferred embodiment of this invention, the bit puller and outer frame or brace are rotatable relative to each other. This permits the user of the tool to align the sectioned portion of the outer frame or brace with the lateral engagement opening of the bit puller for rapid installation as discussed above. However, it also permits the user to rotate the outer shield or the opening of the connector so that they are not aligned during separation of the cutting bit from the cutting bit holder. This non-alignment greatly reduces the degree of freedom available to the cutting bit after separation
Additional features and advantages of the invention will become apparent to those skilled in the art upon consideration of the following detailed description of a preferred embodiment exemplifying the best mode of carrying out the invention as presently perceived. The detailed description particularly refers to the accompanying figures.